mfd: rtsx: Add support for rts522A

rts522a(rts5227s) is derived from rts5227, and mainly same with rts5227.
Add it to file mfd/rts5227.c to support this chip.

Signed-off-by: Micky Ching <micky_ching@realsil.com.cn>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index d6514fb..2db1337 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -736,9 +736,10 @@
 	select MFD_CORE
 	help
 	  This supports for Realtek PCI-Express card reader including rts5209,
-	  rts5229, rtl8411, etc. Realtek card reader supports access to many
-	  types of memory cards, such as Memory Stick, Memory Stick Pro,
-	  Secure Digital and MultiMediaCard.
+	  rts5227, rts522A, rts5229, rts5249, rts524A, rts525A, rtl8411, etc.
+	  Realtek card reader supports access to many types of memory cards,
+	  such as Memory Stick, Memory Stick Pro, Secure Digital and
+	  MultiMediaCard.
 
 config MFD_RT5033
 	tristate "Richtek RT5033 Power Management IC"